Transcription
If the universe is infinitely big, then
you can pretty much prove mathematically
that there'd be infinite copies of us.
You can absolutely talk about this idea
seriously. Sure, maybe the big bang is
an interesting event, but not the
beginning of time, but maybe the
universe existed before that. Maybe
there were other big bangs that happened
before that. Maybe there's a whole
prehistory leading up to the event that
we call the big bang. You can't have
physics without general relativity and
quantum mechanics playing well together
as string theory is still the most
promising approach.
Host of the interview is Dr. Matt Kowki,
a science popularizer and a former
digital ambassador of the European
Union. What's happened before Big Bang?
No one knows what happened before the
Big Bang. No one even knows if the
concept of before is relevant when you
apply it to the big bang. I mean, before
obviously is relevant to what was I
doing before I got here today or what
was I doing before the election, you
know, a couple weeks ago. All those
notions of before make sense. But the
big bang may be the moment where time
itself began. And if that's the case, to
talk about before the Big Bang would be
to talk about a time when there was no
time. And so it'd be an incoherent
notion. That's one possibility. The
other possibility is, sure, maybe the
Big Bang is an interesting event, but
not the beginning of time, not the
beginning of everything. Maybe the Big
Bang is an
interesting realm in which the universe
swelled rapidly. That's what we mean by
the Big Bang. But maybe the universe
existed before that. Maybe there were
other big bangs that happened before
that. Maybe there's a whole prehistory
leading up to the event that we call the
big bang. As of today, nobody knows
which or if any of these perspectives is
correct. Did time have beginning? Did
time have a beginning? Nobody knows. In
our theories, mathematical theories, we
always assume that there is time from
the get-go. We don't even know how to
formulate physical laws without assuming
that time exists. So our mathematics
gives us no insight into whether there
is an origin to time or whether there
might even be a realm where there is no
time. There is no space. And only when
the ingredients in that realm that we
can't fully describe, when they arrange
themselves correctly, then space and
time as we know them emerge. We don't
know if that's a sensible way of
thinking about reality, but it certainly
is a compelling one to imagine that as a
possibility. Maybe time is the illusion
of our brain, of our mind. Time could
certainly be a human construct. Time
could be something that we impose on the
external world because it allows us to
organize events. And when we can
organize events, we can find coherence.
We can find patterns. We can describe it
all mathematically. But sure, can I
imagine that we encounter some alien
civilization in the far future and their
conception of reality doesn't involve
time at all or maybe as fundamentally as
our conception does? That they organize
events according to a completely
different framework that does not
involve moment after moment after
moment. that their experience is not
felt as moment after moment after moment
as our experience is. Can I imagine
that? Yeah, I can. Did universe begin
from something small like a pin? Is it
possible?
Sure. In the conventional approach to
the big bang which often goes under the
name of inflationary cosmology, we
imagine that there was a little tiny
pike sized part of space that was filled
with a certain kind of cosmic fuel. It's
called the inflaton field. Name doesn't
matter but this fuel gives rise to
powerful repulsive gravity. That's a
weird idea. We are used to gravity
that's attractive. You drop something,
it falls to the earth because the earth
and the object attract one another. We
have never directly experienced
repulsive gravity, but Einstein's
equations from general relativity say
that it is real, that it does exist. And
so imagine you have a little pe like
shape that's filled with this fuel that
gives rise to repulsive
gravity causing it to rapidly swell, to
blow apart. That's what we think may
have been the big bang. And so, yes,
everything would have started from an
incredibly small but dense, highly
energetic starting point that gave rise
to the big bang. We can use the
inflationary theory together with our
understanding of the electromagnetic
force and the nuclear forces. We can use
powerful computers to simulate what the
universe will look like after this rapid
swelling. And we understand the
formation of stars and galaxies. Not in
every detail by any means, but we can
understand the processes well enough to
get a sense of what the universe should
look like on its largest of scales. And
amazingly, while we don't have all the
details, what our computers predict is
pretty close to what we see. And that's
an amazing achievement. cosmological
landscape changed your life? Well, all
of these ideas have changed my life
because my perspective is guided by my
understanding of reality. And so, as I
learned quantum mechanics, my sense of
reality began to shift. And so, I and my
engagement with the world began to
shift. When I learned the general theory
of relativity, the same thing happened.
These were wondrous educational moments
for me. It wasn't just learning about
warps and curves in the fabric of space.
I felt like I knew the universe better.
I understood it better. I could engage
with it more richly. And sure, these
more speculative ideas that there might
be other universes out there. Does that
change my view? It enriches it as a real
possibility that this reality might be
one of many. How could knowledge of
these ideas not then backreact on your
own view of who you are and how you fit
in? It does. Infinitive universes. Do
you believe that it could exist? I think
the possibility of infinite universes
is an idea worth having in your toolkit
because a it naturally emerges from a
variety of ideas from the inflationary
theory to the many worlds interpretation
of quantum mechanics. So it may be true
and if it is true it completely changes
the landscape of reality. And so for me
to sit here and imagine there might be a
copy of me out there in the cosmos
infinite copy of us. If the universe is
infinitely big then you can pretty much
prove mathematically that there'd be
infinite copies of us out there one
after another after another. Sometimes
having exactly the same conversations
sometimes having slightly different
conversations. That's a crazy idea. But
is it the idea or theory real theory?
You can absolutely talk about this idea
seriously if you're willing to make an
assumption. And that assumption you
should realize could be wrong. The
assumption is does space go on
infinitely far. Or could it be that you
go out sufficiently distant and you
maybe circle back to your starting point
as would happen on the surface of the
earth? We don't know the answer. But
under the assumption that space goes on
infinitely far, you can argue
convincingly with mathematics that there
would be copies of us out there.
Infinity universes can be connected with
our
universe. Connections between the
different universes depends on the
flavor of the multiverse that you look
at. If you're thinking about an
infinitely large universe, then yeah, in
principle you could start here and in
principle you could pass through those
universes, if you had enough longevity
and if you could travel fast enough. But
there are other versions of infinite
universes such as that from quantum
mechanics where you really couldn't jump
from one universe to another. That's not
the way that version of the multiverse
emerges. So it's completely dependent on
the flavor of multiverse that you're
interested in. 26 years ago your
bestseller elegant universe was was
published. You spend so much time string
theory. Today when I'm talking with
scientists they mostly say it's a
beautiful mathematical idea but it
doesn't exist. We have no proof.
uh and on the Washington Post your last
one article that we should still conduct
research regarding string theory doesn't
matter that we have no proof why you
believe still that string theory it's um
serious theory that we should be focused
so I would agree with all of those that
you make reference to you agree I agree
with I agree with all of those who
you've made reference to, at least if
your summary is an accurate depiction of
their perspective. I agree that string
theory is a beautiful mathematical
structure. I agree that there is zero
experimental or observational data
establishing that string theory is the
correct theory of the universe. So what
do you do? And it doesn't work when we
have more than 11 dimensions. And the
theory
absolutely requires that the fabric of
space be far more subtle and rich than
Einstein himself or Newton would have
thought. The possibility of extra
dimensions is a natural consequence of
string theory. All of this is true.
Nevertheless, string theory does have
the capacity to describe the world as we
know it. Is it the right theory? We
don't know. And so as the most promising
approach that we have yet found for
putting Einstein's ideas of gravity
together with the laws of quantum
physics, a union that has to happen. You
can't have physics without general
relativity and quantum mechanics playing
well together. As string theory is still
the most promising approach. Of course,
we should pursue it mathematically,
vigorously, seeking to extract some
observation or experiment that maybe one
day we can carry out. But as I said in
the Washington Post article, if somebody
comes along tomorrow and shows that
there's a mathematical flaw in string
theory, we should abandon it. This has
never happened. If tomorrow somebody
should come along and say, "Look at this
new idea that we can put general
relativity and quantum mechanics
together and it's immediately close to
the world and we can test it and let's
go." Of course, I'd be excited and I
would jump at that possibility as a new
direction to pursue. So, I'm not sitting
here dogmatically saying string theory,
string theory. No, not at all. I'm
saying truth, truth. Let's try to find
things that take us closer to truth. At
the moment, that is string theory in
terms of putting the laws of physics
into a unified framework. But is it
possible that we'll have something else
3 years, 5 years, 100 years that string
theory will be relegated to the dust bin
of science? Is that possible? Of course,
it's possible. Maybe Twister story will
replace string theory. Look, Roger
Penrose did a remarkable job. years old.
So he did a remarkable job in developing
the twister idea and there's beautiful
mathematics within twister theory and in
fact there are subtle ways that the
twister idea has been in dialogue with
string theory. It's not as though these
ideas are at opposite ends of some kind
of theory spectrum. And so yes, is it
possible that there's some deep truth in
Roger's approach? Yes. Is it possible
that there's some deep truth in the
string theoretic approach? Yes. How will
we figure it out? Continue to work to
develop the equations, develop the
mathematics, extract whatever insight we
can into the theories. That's the only
way to answer those deep questions. Do
you believe that we'll ever find answer
what connect quantum world and classical
reality?
That is a big question. the biggest the
the well yeah it's among the biggest
questions how to go from the quantum
dis on the quantum level to the real
Newtonian reality yeah I mean we're
still struggling even and this is an
important lesson we're still now
struggling 100 years after quantum
mechanics was written down by Heisenberg
and Schroinger this is 1925 and 1926
100red years later we can use the
equations to make predictions that are
borne out by experiment. We can use the
equations to engineer things like
integrated circuits making everything
from, you know, cell phones to laptop
computers that have revolutionized life
on this planet. And yet, even with those
successes, there are deep questions
within quantum mechanics that we've yet
to resolve. And the biggest one is how
do you go from the quantum description
of a reality that is described as a
fuzzy haze of probabilities which is the
language of quantum physics. How do you
go from that to the definite reality
that we all experience every moment of
our lives? What's the transition from
the quantum to the matter is transformed
from the quantum world to classical
reality? Yes, that's the deep question.
Now there are many physicists who think
that's a
nonquest. Neils Boore, founder of
quantum mechanics, thought that was a
non question. He said you're thinking
about things wrong. You're stuck in an
old mindset. The new mindset, Bore said,
is you have a realm of classical
equipment and that's the stuff that we
see in laboratories and you always use
the classical language to describe those
things. And then when you're talking
about the molecules and atoms and
particles, you use the quantum language
only down there. The problem with that
perspective is that the equipment is
made of the very same ingredients that
you use quantum mechanics to describe.
It's made of the electrons and the part
protons and the neutrons. And so if
quantum mechanics describes the
ingredients in the equipment, then it
must describe the equipment, which is
nothing but a conglomeration of the
ingredients. And it's that step that
bore would somehow resist and it's that
step that we are still struggling to
understand. Quantum mechanics is for you
local or non-local. Quantum mechanics as
far as we can tell is non-local. And
this is one of the deep insights that
came from the work of John Bell working
in the 1960s. A name that most people
have never heard of. Everybody knows
Einstein. They should because it was
John Bell almost as a hobby. He was
working at CERN particle accelerator was
working on other things. But in his
spare time like to think about the
foundations of quantum mechanics and in
his work he was able to reveal a test to
determine whether or not certain ideas
that Einstein had that the universe was
local what you do here only affects
things here and that it was real that
particles always have definite features.
He came up with a test of Einstein's
view. Nobody thought you could test
Einstein's view. It was just metaphysics
ideas. Go away Einstein. You're just
thinking philosophy. We're physicists.
Which is basically what people said
toward the latter decades of Einstein's
life. But John Bell said, "No, no, no.
This is not just philosophy. This is
physics. We can actually test whether
these things Einstein was saying are
true." And when the tests were done,
they to most people's satisfaction
revealed that Einstein's view that the
universe was local. That that was not
true. That the universe is non-local. In
a sense, what you do here can in a very
specific quantum way be connected to
something that happens over there. If
you could find just only one answer for
just only one question about the
reality, what it would be? I would like
to understand the nature of time. Is
time something that we impose from our
minds or is it somehow intrinsic to the
structure of reality? That would be one
big one. But if you let me even dream
even bigger, the biggest question of all
is why is there something rather than
nothing? Not empty space, nothing, but
why is there anything at all? Logically,
you could imagine the absence of space
and time and matter and energy and
everything. What brought existence into
being? But outside the universe, there
is nothing. We don't know if there's
even a notion of outside the universe.
The deepest unresolved question at the
heart of quantum
mechanics. How does the probability
quantum haze transition in the defined
reality of everyday experience? Yeah.
Could you answer for that question? I
don't know an answer to that question.
That is the question that we were
discussing before. What is the means by
which a description of the world in
terms of probabilities turns into an
experience of the world that is
absolutely definite? How does that
transition take place? We've made a lot
of headway with ideas of so-called
decoherence and things of that sort, but
in terms of truly answering the
so-called quantum measurement problem,
nobody knows the answer. What are you
doing now? Tell me something about your
actual research. What are you doing now
at Colombia University? Yeah. So, right
now with a number of colleagues, we've
been studying the possibility that the
extra dimensions might have yet weirder
properties. Your mind is dimensional.
You are still thinking about dimensions.
Yeah, we're certainly still thinking
about extra dimensions. The possibility
that the extra dimensions might allow
you to circumn them. Maybe the extra
dimensions is a large circle, a shape
that you can fully transverse. And the
reason this turns out to be interesting,
we found that in these possible
scenarios, you could send a signal from
here to someplace far away and it could
get there faster than the speed of
light. Faster than the speed of light.
It's impossible. That's what most people
would say and that's what we thought
too. But it turns out if you send the
signal Einstein said that it's
impossible with a speed faster than
light doesn't exist. So we're completely
compatible with Einstein because locally
the speed of the signal is always equal
to light speed. But if you have an extra
dimension, there's two trajectories to
go from here to here. There's the direct
one from here to here, but there's the
indirect one where you spiral around the
extra dimension and get there. You would
think that spiraling around would take
you longer, but it doesn't. Even going
at light speed, you can beat the signal
that goes from here to there directly.
Effectively sending a signal from here
to there at faster than the speed of
light. It's just only that theoretical.
Everything I do is theoretical.
Everything I do is mathematical. And so
yes, this is under the assumption the
assumption that there's an extra
dimension in the shape of say a circle.
It's also making the assumption that we
live on a so-called membrane in string
theory that's moving along this extra
dimension. There's a whole set of
assumptions, but
remarkably with those assumptions, you
can send a signal from here to there at
faster than the speed of light. Do you
believe that we can ever achieve
something called AGI, strong AI,
superhumans AI? Without a doubt, I
believe that there's no obstacle
fundamentally to the capacities of these
artificially intelligent systems. Look,
I don't think there's anything special
about the biological brain that gives
rise to consciousness and intelligence.
I think that if you were to engineer a
version of what's inside of our heads in
silicon that in principle it could think
and feel and be intelligent and there'd
be nothing in principle stopping you
from cramming information and capacity
and and and chips and circuits that will
allow that artificial structure to
operate at a level that's beyond our
capacity. So do I think that we will get
there? I do. And I don't think it's far
away either. Yeah, it's for you more
something more than just only
statistical. Look, the approach that the
large language models have been
following is certainly one way. It is a
statistical approach based on large data
sets. But that's not the only way that
researchers have been and will continue
to try to achieve artificial general
intelligence. You could couple those
statistics with some model of the
external world, with some understanding
of the fundamental laws of physics, some
understanding of what we have already
learned in a very concrete framework.
That additional structure by itself in
principle could allow the probabilities
to get you to results that are more
relevant, more insightful. And so that
would be a more intelligent system
compared to one that's based purely on
the statistics. And that's merely one
approach. You've got some of the most
creative thinkers in the world that are
researching ways to make these systems
ever better. And I don't see any limit
to what it is that they can achieve. A
lot of people think that even our
language it's not enough to describe
what we created because AI the world AI
it's not artificial. It's real. Yeah. We
have also not one artificial
intelligent. We have archipelago of
islands that of course we integrate each
other but still there is not one
continent. Yes, I fully agree. The whole
notion
that intelligence can be organic or
artificial is itself an artificial
distinction. Right? You have systems
that can take in information and produce
useful information as output. And
whether that system happened to emerge
through the ordinary biological process
of a living system maturing or through
some system that we build. Well, it
doesn't really matter in the end of the
day. It determines on input versus
output. And if you can build some system
that is intelligent, it is a new kind of
intelligence, not necessarily an
artificial version of intelligence. I
have two final questions to you. The
first one is about your own congress,
World Science Congress. Why you founded
that? World Science Festival. Yeah. Why
science festival? Well, way back when we
began the World Science Festival, we
recognized an opportunity to get people
excited about forefront ideas in
physics, in mathematics, in computer
science, in cosmology, in chemistry and
biology. And so we said, why don't we
create a gathering place where we'll
bring the world's leading scientists to
be in direct conversation with the
general public? And so this idea caught
on and you know at our first gathering
we had 120,000 people come to the events
and so we recognized that we had really
tapped into something that mattered to
people and so we've been pursuing it
ever since. Who today inspired you the
most? Who was your master? Your father a
musician or Yeah, my father had a had a
profound impact on me. And today, well,
my dad was a musician and a composer who
did not have even a high school
education, but was deeply interested in
the world and he was seeing it from the
perspective of art, perspective of music
and that inspired me that there are so
many different ways to understand
reality and each of them gives you new
insights and so that's why I don't spend
my time just doing physics per se and I
think my father's influence is a big
part of that I want to understand the
various ways of seeing into the workings
of the world. Be it from art, science,
literature, music, all of these provide
a more rich engagement with reality.
Thank you for your time. My pleasure.
Thank you.